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Message |
    
Brianentz
Tinkerer
Username: Brianentz
Post Number: 1
Registered: 09-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 22, 2011 - 12:54 pm: | 
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I just picked up a canonet ql17 G-III from ebay. My first rangefinder. I put a brand new battery in it that is supposed to be for this camera, but when I push the battery light button nothing lights up. And the metering needle inside doesn't move out of its position just below 5.6. (Not to mention it needs new seals ... BAD). I know the shutters are mechanical and seem OK. How can I verify if this camera has electrical problems (maybe the bulb is out and maybe I just don't understand how the meter needle is supposed to work) and if so what can be done? |
Jimmyh
Tinkerer
Username: Jimmyh
Post Number: 4
Registered: 04-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 22, 2011 - 01:25 pm: |
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I just checked mine, which I haven't used in a long time.
With the aperture ring set to "A" and, the lens cap off, the needle moves in response to changing light conditions without pressing any buttons or manipulating any controls. Pressing on the red button lights the Check LED on the back. I would guess this is how it is supposed to work.
If you get no Check LED, be sure your battery itself is OK (check with a voltmeter) and inserted correctly. Also, check the battery contacts for corrosion and that it applies enough pressure to contact the battery properly.
After that, I'm out of ideas... |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 92
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 22, 2011 - 01:30 pm: |
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First, check and clean the battery contacts. Even if they look clean, wipe them off with some alcohol or a pencil erasor. Make sure you are putting the battery in correctly.
If that doesn't help, the next thing to check is the wiring from the battery compartment. It may be corroded even if the battery compartment itself is clean. The bottom of the camera can be removed easily by removing the small screws. Just be careful not to lose the small spring that holds the battery door in place. If the wires are corroded, they may need to be re-soldered. Sometimes the wires need to be replaced entirely, as the corrosion has travelled further up the length of the wire.
One thing that troubles me, is that you said the needle is sitting just below 5.6. This doesn't sound correct. It should be at the bottom of the scale when there is no battery. This could mean the needle is stuck. |
Brianentz
Tinkerer
Username: Brianentz
Post Number: 2
Registered: 09-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 23, 2011 - 09:56 am: |
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if the needle is stuck, what then? Any idea on how to repair? |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 93
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 23, 2011 - 10:41 am: |
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Well, hopefully it is not the case but...
If it is stuck, you will need to remove the top to gain access. If you look on this forum under the repair manual section, you will find assembly drawings for the GIII. It is not a difficult job do.
Sometimes the magnet that is part of the meter assembly will pick up some dirt or debris and will interfere with the movement of the needle. If it is cleaned it should work properly.
You won't know exactly what the problem is until you open the camera up. |
Brianentz
Tinkerer
Username: Brianentz
Post Number: 3
Registered: 09-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, September 24, 2011 - 12:02 am: |
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I removed the top to gain access and the needle does appear to move freely. However, gently pushing it up it doesn't want to go all the way up. Gently pushing it down it goes all the way down. I don't know if that's normal or not. It seems to want to settle back around 5.6. I blew the area out with my blower. Toward the left of the needle the far end of the needle moves within a semicircle notched area but again it will only go so far down (only allowing the needle to go so far up) without some undue pressure. It seems clear it has been worked on before. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 94
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, September 25, 2011 - 07:40 am: |
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I have not worked directly on a GIII meter, but it is a trap needle design. The needle moves up and down based on the level of light. As you press the shutter button, the needle is trapped by a serrated linkage which is translated (mechanically) to the diaphragm in the lens to set the proper aperture. It sounds like the needle may be trapped somewhere in the middle, rather than swinging freely when no battery is present. If it has been serviced before, it may have been assembled incorrecty. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 98
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 27, 2011 - 12:21 pm: |
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Ok, here's the bad news...
If the needle is floating, ie. reading light when it should not be, it may be that the Cds cell is dying. It seems to be the case with my Konica.
Basically, the Cds cell is a variable resistor. If there is lots of light, there is no resistance and the needle spikes to the top of the scale. When there is no light, there is maximum resistance and the circuit is closed.
In your case, the Cds is showing less resistance than it should, therefore the camera thinks there is light when there actually isn't.
I have not seen this problem before, but apparently this is symptomatic of a dying Cds cell. |
